Lady Sibylla Zosimus (née Andronikos) was a Tyran noblewoman of Zantine descent. She was the wife of Lord Hugh Zosimus of Tyr and mother to his sons Stephen and Gavin Zosimus. She is the paternal grandmother of Queen Laura Stirling, and the great-grandmother of King Richard and Princess Eleanor.
She outlived her husband and managed his fortune until her death. During that time, Stephen died and Gavin eloped with a servant, Melissa, prompting her to disinherit him. Melissa died, and upon hearing his mother was on her deathbed, Gavin returned to Tyr to reconcile with her. Before her death she made him her heir again, but her plans were thwarted by King Tristan, who interfered and made her nephew-in-law, Lucan Zosimus, the new lord.